Ashless dispersants suitable for use in lubricating oil are known. One such additive is made by reacting a hydrocarbon-substituted succinic anhydride with an amine such as ethylene polyamine (U.S. Pat. No. 3,272,746). More recently, effective dispersants have been made by grafting maleic anhydride and a co-monomer such as alkyl methacrylate onto a high molecular weight olefin backbone followed by amidation (U.S. Pat. No. 4,160,739). Another effective dispersant can be made by simply grafting a vinyl-substituted nitrogen compound such as vinyl pyridine or N-vinyl pyrrolidone onto a high molecular weight olefin backbone (U.S. Pat. No. 4,146,489).